Draft reference · October 2026

Wiring

Draft. This is the harness of the prototype being built now. It will be checked on the prototype and corrected before the verified release. Read the safety reference before working on the battery.

This page covers the battery builds (main, MP80100 and C80100). The Lite (wall power) is summarized at the end.

Every wire below is routed through the enclosure in the design model with its real insulation diameter, so the lengths are routed lengths: add 10-15 % for the terminations. Gauges are minimums.

Parts in the harness

Power path

flowchart LR
  A["Pack A 5S"] -- "series link (EC5)" --> B["Pack B 5S"]
  B -- "B+ 10 AWG" --> FB["MRBF block<br/>battery-end stud (M5)"]
  FB --> F40["40 A 58 V fuse"] --> FO["output stud (M8)"]
  FO -- "10 AWG" --> OD["ODrive Pro DC+"]
  FO -- "18 AWG" --> F3["3 A 58 V fuse"] --> REG["5 V regulator<br/>Pololu D42V55F5"]
  CH["XT60E-F charge port +"] -- "16 AWG" --> F10["10 A 58 V fuse"] --> FB
  A -- "A- 10 AWG" --> BMS["BMS B-<br/>JBD 10S"]
  BMS -- "P- 10 AWG" --> W["WAGO 221-615<br/>P- junction"]
  W -- "10 AWG" --> ODM["ODrive Pro DC-"]
  W -- "16 AWG" --> CHM["charge port -"]
  W -- "18 AWG" --> REG
  SW["Power button"] -- "signal pair" --> BMS
  REG -- "5 V" --> PI["Raspberry Pi 4"]
  REG -- "5 V" --> T["Teensy 4.0"]
  REG -- "5 V" --> FAN["ODrive fan"]
  T -- "CAN" --> CANB["SN65HVD230"] -- "CAN H/L" --> OD
  T -- "USB" --> PI

Every return goes through the BMS P- (the WAGO), so the BMS can switch everything off. Charging enters at the fuse block's battery-end stud through its own 10 A fuse: it bypasses the 40 A fuse, and the BMS still controls it. Regenerative braking current flows back through the 40 A fuse and the BMS into the pack.

Wire list

Notes

• Every fuse and fuse holder must be rated 58 V DC. Common 32 V automotive MINI blades and holders are not rated for a 42 V pack.
• Ring terminals: 10 AWG with an M5 hole (pack +) and 16 AWG with an M5 hole (charge +) under the battery-end washer; 10 AWG with a 5/16 in (M8) hole (ODrive DC+) and 18 AWG with a 5/16 in hole (regulator feed) on the output stud. Tighten the M8 nut to 75 in-lb maximum, then fit the block's insulating cover.
• The EC5 plugs on the pack leads are the service disconnect. Plug them in with the BMS switched off.
• BMS: configure it for 10S and set over-charge to 4.20-4.25 V per cell in its app (some boards ship with LiFePO4 settings). Check that your board has the soft-switch connector before you build the harness round it.
• WAGO 221-615 is rated about 30 A (UL). The peak battery current is about 28 A for short pulls.
• Teensy: cut the VIN-VUSB pad. It is powered by the regulator and also connected to the Pi by USB.
• Motor phase leads: the gauge and exit point depend on your motor. The design assumes 12 AWG through a 12 mm grommet, along the notches in the corner brackets.
• Crimp ferrules on every wire into the ODrive terminal block.
• Charger: 42.0 V (10S) Li-ion/LiPo CC/CV, 2-4 A, with an XT60 male plug. Charge only through the charge port, with the BMS connected.
• First power-up: the ODrive's input capacitors can trip the BMS's short-circuit protection at switch-on. If it does, lengthen the BMS short-circuit delay in its app.

Lite (wall power)

The Lite has no battery, BMS, main fuse block, WAGO, charge port or power button. Its harness (22 wires):

• Mains: an IEC C14 inlet in the right cover's back step. Line runs through the rocker switch to the supply's AC input (CN1), neutral straight to CN1. Earth runs from the inlet to the supply's earth screw and on to the M4 earth stud in the base plate. Use insulated 6.3 mm quick-disconnects on the inlet and switch tabs.
• DC: 10 AWG from the Mean Well LOP-600-36 (36 V) to the ODrive S1's DC pads.
• Motor: the three phases along the same floor channel as the battery build, to the S1's phase pads.
• Brake resistor: two 1 Ω, 50 W resistors in series (2 Ω) on the base plate, to the S1's R+ and R- pads. Regenerative energy goes into them, not into the supply.
• 5 V: the regulator is fed from the supply's 12 V auxiliary output (CN2) and powers the fan and the XIAO ESP32-C3.
• Signals: the XIAO to the CAN board, CAN from the CAN board to the S1 (4-pin JST-GH), and the knob (EC11) to the XIAO.

Mains wiring can kill. Have it checked by someone qualified, check earth continuity from the inlet's earth pin to the base plate and the rear plate, and keep the covers on whenever the unit is plugged in.

A draft reference: the prototype is being built and tested, and the CAD, build files and software are released after testing.